The present invention relates to a fluid coupling for use with textile machines, particularly but not exclusively filament winders of the type known as bobbin revolvers.
A bobbin revolver is a machine for winding synthetic filaments; the latter term is here intended to cover continuous lengths of mono-filamentary and multi-filamentary materials. Such materials must be continuously wound on a suitable bobbin tube as they leave the spinneret or a preceding process. A bobbin revolver is designed to carry a plurality of bobbin tubes (usually two) so that when a yarn package upon one of the bobbin tubes is complete, the yarn can be quickly transferred to another tube of said plurality and winding can continue without interruption. Such machines are already well known in the filament winding art; one example of such a machine is described in the British Pat. No. 1,332,182. A development of that machine is described in recently filed U.S. Patent Application Ser. No. 945,330 herein referred to as prior Application. The full disclosure of British Patent No. 1,332,182 and the prior application is hereby incorporated in the present specification by reference.
The machines described in the Patent and prior application above referred to are of a generally known type comprising a positively driven drum as the main drive element for the bobbin tubes. The bobbin tubes can be brought successively into a winding condition in frictional contact with the drive drum, the tubes themselves being mounted on respective chucks which are freely rotatable on chuck shafts provided on the revolver. In such a machine it is desirable to maintain a controlled pressure between the friction drive drum and the bobbin tube or package thereon during a wind. While it is not essential to hold this pressure precisely constant, it is highly desirable that the pressure be held within certain definite limits dependant upon the particular machine or type of yarn to be wound.
Movement of bobbin tubes between winding and non-winding conditions involves rotation of a chuck carrier about a predetermined axis. There is almost always at least one fluid operated device on the rotatable chuck carrier. For example, each chuck will include a clamping device for releasably clamping a bobbin tube in place thereon; it is conventional practice to operate this clamping device by compressed air, at least to cause release of the bobbin tube even if the main clamping effect is achieved by spring operated means. In the more highly developed bobbin revolver described in the prior application, there is in addition a plurality of piston and cylinder units designed to enable adjustment of the positions of the individual chucks on the chuck carrier. Attention is drawn to these fluid operated devices by way of example only; the precise purpose for which pressure fluid is required on the chuck carrier is not important to the present invention.
There is another known form of bobbin revolver in which there is a demand for pressure fluid on a rotatable chuck carrier, namely that described in Japanese Utility Model No. 8739/53 (published Mar. 7, 1978). That specification describes a form of fluid coupling comprising a collar fitted to and rotatable with a shaft which rotates the chuck support. The collar is located within a sleeve and is provided with a plurality of annular grooves facing outwardly towards the sleeve. A corresponding plurality of O-ring seals are provided between the collar and the sleeve so that the grooves are isolated from each other. A plurality of passages lead from respective grooves through the collar to respective tubes which in use communicate with the pressure fluid operated devices on the chuck carrier. Also, a plurality of openings in the sleeve pass from respective grooves to the exterior of the sleeve. The latter is connected to the fixed housing of the machine, so that tubes can be connected to the exterior openings to enable pressure fluid to be fed to the associated grooves. With such an arrangement, the pressure operated devices on the chuck support can be supplied with operating fluid at any angular disposition of the chuck support because the passages in the collar are in permanent communication with their respective grooves.
The bobbin revolver shown in Japanese specification differs, however, from the other revolvers referred to above, in that the chuck shafts are positively driven by individual motors which are mounted on the chuck support. Accordingly, that machine does not require a friction drive drum, and there is no need for accurate control of a winding pressure exerted between the friction drive drum and a bobbin tube or package driven thereby. There is a substantial disadvantage to the fluid coupling described in the Japanese specification when it is applied to a bobbin revolver adapted for use with a friction drive drum and in which it is desired to maintain in use a controlled force urging a chuck towards a friction drive drum by way of the operating system for rotating the chuck carrier. Sliding friction between the two elements of the coupling, the collar and sleeve referred to above, is substantially uncontrollable and produces unacceptable variations in the winding pressure between different machines and possibly even on the same machine between different operating conditions. The machine manufacturer is therefore faced with the problem of individually adjusting each machine to take account of the individual friction performance of the fluid coupling in that machine, and the machine user may be faced with the problem of adjusting the machine to account for different operating circumstances over time.